KEY: S = Estimate does not meet publication standards because of high
sampling variability or poor response quality. - = Zero or Less than half the
unit shown; thus, it has been rounded to zero.

1 Ton-miles estimates are based on
estimated distances traveled along a modeled transportation network. 2 Coefficient of Variation.

NOTES: Value-of-shipments estimates have not been adjusted for price
changes. Estimated measures of sampling variability for each estimate known
as coefficients of variation (CV) are also provided in these tables. More
information on sampling error, confidentiality protection, nonsampling error,
sample design, and definitions may be found at http://www.bts.gov/publications/commodity_flow_survey/.

SOURCE: U.S. Department of Transportation, Research and Innovative
Technology Administration, Bureau of Transportation Statistics and U.S.
Department of Commerce, U.S. Census Bureau, 2007 Economic Census:
Transportation Commodity Flow Survey, December 2009.